1. Field of the Invention
The present invention relates to novel benzyl-substituted photoactive compounds and photoresist compositions comprising such compounds.
2. Background Art
Photoresists are photosensitive films used for transfer of images to a substrate. They can form negative or positive images. After a coating layer of a photoresist is formed on a substrate, the coating is selectively exposed through a photomask to a source of activating energy such as ultraviolet light. The photomask has areas that are opaque to activating radiation and other areas that are transparent to activating radiation. The pattern in the photomask of opaque and transparent areas defines a desired image to be transferred to a substrate. A relief image is provided upon development of the latent image patterned in the resist coating. The use of photoresists are generally described, for example, in Deforest, Photoresist Materials and Processes, McGraw Hill Book Company, New York (1975) and in Moreau, Semiconductor Lithography, Principles, Practices and Materials, Plenum Press, New York (1988), both incorporated herein by reference.
Various attempts have been made to alter the make-up of photoresist compositions to improve performance of functional properties. In particular, a variety of photoactive compounds have been reported for use in photoresist compositions.
Relatively recently interest has increased in photoresists that can be photoimaged with deep U.V. radiation. Such photoresists offer the potential of forming images of smaller features than may be possible at longer wavelength exposure. As is recognized by those in the art "deep U.V. radiation" refers to exposure radiation having a wavelength in the range of about 350 nm or less, more typically is the range of about 300 nm or less. While a number of photoactive compounds have been reported for use at deep U.V. exposure wavelengths, the need exists for new compounds suitable for use as a photoactive component in photoresist compositions, particularly new photoactive compounds that can be activated by deep U.V. radiation.